الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The importance of windbreak plantation by the use of different woody tree species in order to protect the grow i ng crops 1 s 1 ncreased a 11 over the w or 1 d. And more seri ous 1 y 1 n the 1 ess-deve 1 op i ng countrl es w h i ch suffer from food and forage shortage. Our country is am ong these nat ions, and in part i cu 1 ar, the desert Governorates such as New Valley, Red Sea, Sinai and Marsa Matrouh. Windbreak plants cou 1 d protect d iff erent agrl cu 1 tura 1 crops by the 1 r capability of modifying and re1iefing the adverse effects of env i ronm enta I cond it ions aff ect i ng grow th and development of agricultural crops. Among the most popular
wjndbreakers are casuarina equisetifolia and Eucalyus
cama1du1ensis which were examined in. the present
Investigation during two consecutive seasons, 1992 and \993 .
A Field experiment was executed at Dakh1a, New Valley
Governorate to investigate the effect of six windbreak systems (single, double and triple rows of each of (Casuarina equisetifo1ia and Euca1ytus cama1du1ensis) and NPK fertilization rates on vegetative growth and
hem i ca 1 const i tuents of windbreak plants. I n add it i on, the d iff erent windbreak system s on the protected TOP aHa aHa was also explored.
Obtained results could be summarized in the following aragraphs
* Effect of windbreak System on vegetat ive Growth and Chem i ca 1 Const i tuents of Windbreaks
plants height of windbreak plants was gradually
Increased by the use of tri pIe row system of either
species, Casuarina or Eucalyptus,
* Contrary from plant height, single row system
for e Hher Casuari na or Euca lyptus produced the th 1 ckest
stem diameter followed by double and then triple row
system It was not iced that Euca Iyptus plants were
thl cker than the correspond 1 ng systems of Casuarl na
plants.
* Number of branches per p I ant took the same trend that of stem diameter, It was gradually lncteased by the use of single, double and then triple row system of either spec 1 es w Hh casuarl na p I ants ho I ding more branches than the corresponding row system of. Eucalyptus.
* The heaviest fresh and dry weights of leaves Within each one of the two species were obtained from single row, followed by doub I e and then the trl pIe ones. Moreover, casuarl ng p I ants ho 1 d peronounc 1 y heav 1 er I eaves fresh and
~ry weights than similar Eucalyptus arrangement system ~ld.
* The contents of chlorophyll a and band carotenolds In
the leaves of different windbreak systems were not
learly affected by eow system of eHher species.
* Leaces nHrogen and potassium percents were
\lgn i f i cant 1 y higher for Euca 1 yptus than those 1 n casuarl na
egard I ess of windbreak structure of, e Hher spec 1 es. Wh II e, o diff erences were detected concern 1 ng 1 eaves shosphorus :ontent .
increased by the use of triple row system of e1ther
spec 1 es, Casuar1 na or Euca 1 yptus.
* Contrary from plant he1ght, s1ng1e row system
for e 1ther Casuar1 na or Euca 1yptus produced the th 1 ckest
stem d1ameter followed by double and then tr1p1e row
system It was noticed that Eucalyptus plants were
th1 cker than the correspond 1 ng system s of Casuar1 na
plants.
* Number of branches per plant took the same trend like that of stem diameter. I t was gradually 1ncteased by the use of s1ng1e, double and then tr1p1e row system of either spec1es with casuarina plants ho1d1ng more branches than the corresponding row system of- Eucalyptus.
* The heaviest fresh and dry weights of leaves w1thln each one of the two species were obtained from s1ng1e row, fo 11 owed by doub 1 e and then the tri p 1 e ones. Moreover, casuar1 ng plants ho 1 d peronounc 1 y heav I er 1 eaves fresh and dry we1 ghts than s1 m 11ar Euca 1yptus arrangement system did.
* The contents of ch 1 orophy 11 a and band caroteno 1 ds 1 n
the leaves of different windbreak systems were not
clearly affected by eow system of either spec1es.
* Leaces nitrogen and potass 1 um percents were
sIgn if i cant 1 y higher for Euca 1 yptus than those 1 n casuar1 na regard 1 e s s 0 f win d b rea k s t r u c t u reo fie it he r s p e c i e s . W h 11 e, no d iff erences were detected concern 1 ng 1 eaves shosphorus content .
* Concernlng leaves uptake of nitrogen, phosphorus ana oat~~~ (UM, the highest va 1 ues of those three const ltuents were those obtained from single row, followed by double and then trl p 1 e row systems of e 1 ther casuarl na or Euca 1 yptus. I n add It lon, the 1 eaves of casuari na were found to contaln much more nltrogen, phosphorus and potassium than the i r correspondl ng system s of Euca 1 yptus.
vegetat ive Grow th and
of Windbreaks : -
* Plant height was gradually 1ncreased b’y the gradual Increase 1n the rate of NPK. Both med1um (N2P 2K2) and high (N3P 3K3) rates w ere, a 1 most equa 11y, effect 1 ve 1 n produc 1 ng the tallest plants with significant differences over low (N1P1K1) and unfert11ized plants.
* A 11 of the three NPK, s 1 gn If 1 cant 1y, produced th 1 cker stems than those of the unf ert 111 zed plants. The. 1 ncrease In d 1 meter was gradua 1 by i ncreas1 ng the fert i 1 1 zat 1 on rate and the maximum was reached w1th N2P2K2 or N3P3K3 rates with unnot 1 ceab 1 e differences between the two rates.
* Supplying casuarina or Eucalyptus plants wlth NPK at any rate enab 1 ed the seed 1 i ngs s 1 gn if i cant ly to carry more branhes than the unf ert i 1 1 zed ones.’ Am ong the three NPK rates no s1 gn i f i cant differences were detected 1 n both seasons but the increase 1 n branch num ber and that 1 n N PK rate w ere par all e 1 .
* Both fresh and dry weights of leaves for all
windbreak systems reached the maximum due to the use of
either medium (N2P2K2) or high (N3P3K3) rates. Both
treatments gave, significantly, higher values in
comparison with low NPK rate and control rate (NoPoKo)’ as well
* The three photosynthet i c pigment contents,
chlorophyll a and b and caroteno i ds, in the leaves of both
casuarina and Eucalyptus were, generally, increasced by
gradua 1 increase in the rate of NPK fertilization. The
maximum contents were obtained from the high NPK rate
* A 11 of the three N, P and K percent in the 1 eaves
gradua 11 y increased by i ncreas i ng the rate of
fertilization with the highest values being due to
medium and high fertilization rates.
* The highest N, P and K leaves
from plants supp 1 i ed with the
fertilization rates (N2P2K2 and N3P3K3), were almost equal in their effectiveness
NPK the
uptake were obtained
highest ewo NPK
Both treatments
** Effect of windbreak Systems on the Protected Crop:-
* All of the six windbreak system s proved to be
effective in producing, significantly, heavier yield of alfa alfa crop than of unprot ected contro 1 crop. I n descend i ng order, tri p 1 e row system of either .casuari ng or Euca 1 yptus species gave the heaviest crop, followed by double eow and then single row , However, on significant differences were detected between
triple and double eow systems in the two seasons.
* Concerning the distance between the windbreak and the protected crop, the heaViest yield was produced from the closest distance (10m) followed by the medium (20 m) and then the farest one (30 m). The increase in the y i e 1 d due to 10 and 20 m planting distance in comparison with 30 m reached 24. 7 and 1 4.9 % in the first season and 29.7 and 16.8 % in the second season, respectively.
* In conclusion, it is recommended to use triple or
doub 1 e windbreak system of either casuaring or Eucalyptus plants and supp ly i ng them with NPK f ert il i zers at the
medium rate N2P 2K2 (40, 30 and 20 g of ammonium
nitrate, calcium superphosphate and potassium sulphate, respectively, per plant or equal units of N, P and K of other commerc i a 1 fert i Ii zers). Such treatment assures the most poteet i on for the protected crop with the most su itab I e grow th of the windbreak plants .